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Topic: rebuilding a 400 (Read 398 times)

just a quick question for anyone more experienced than me (so...everyone) when it comes to engine building.

i have a 400 that i dropped off at the machine shop that i had cleaned, but after life happening and it sitting for a little bit, it started to develop a little bit of surface rust. would it be best if i dropped it off at the shop again to have it cleaned or would a hone to the cylinders and cleaning of the mating surfaces do the trick to start building it work?

If the engine was full of oil and the cylinders were oiled after honing it should be ok if nothing got into it. Might consider taking the heads and oil pan off to give everything a good look if you're not certain. If you're talking about surface rust on the outside of the heads and block then that's just going to happen unless you coat it with a good paint, and one that's heat resistant if you want to last once being used.

I agree that more would see this if in mechanical. I don't usually even check most sections here.

Rust can cause problems. The crosshatching in the cylinders is there to promote good ring seal & hold tiny particles of oil. Enuff rust could prevent the crosshatching from accomplishing it's purpose. I'd probably use at least a 400 grit flex hone to remove light rust in the cylinders. Those hones cost about $100. So, I'd take it back to the shop & see what they say. My guess is they'll recommend removing the rust. But, I've been wrong before.